The present invention relates to a processing module for a modular automation system, for instance a modular stored-programmable control in which the automation system consists of a central unit and of peripheral units that are subordinate to the central unit, for instance input/output modules, the peripheral units being adapted to be connected to each other via a device bus, the processing module including a processor, a memory, a blockable bus coupling element, and a blockable central coupling element, the processor, the memory and the coupling elements being connected to each other by a module bus that is internal to the processing module, the bus coupling element being adapted to be coupled to the device bus, and the central-unit coupling element being adapted to be coupled to the central unit.
A modular automation system is known, for instance, from Federal Republic of Germany 34 18 844 C2. In that automation system, the central unit, in addition to processing the application program, also carries out a number of other tasks, for instance the testing and the monitoring of the peripheral units connected to the central unit. Thus, the central unit is not available solely for processing the application program. In redundant automation systems, the synchronization and data preparation also take place via the central unit. The capacity of the automation system is thereby negatively affected.
U.S. Pat. No. 4,442,504 discloses a modular automation system in which an interface unit is arranged between the central unit and the peripheral units. It serves, among other things, for monitoring and testing the peripheral units.